In this paper we report the European experience with a basket currency, the ECU. The ECU was initially introduced as a reference unit and later became the anchor of the European Monetary System. Public policy was complemented by private sector initiatives and use of the ECU for denomination of financial instruments. In practice, it turned out that a basket currency entails considerable unexpected technical complexities. The technical particularities of a basket currency are discussed before we turn to the criteria for determining the shares of participating currencies. We show that there are no iron-clad economic principles and therefore there is some room for political considerations. In Europe three criteria were used for determining the weights: GDP shares, international trade shares, and financial market indicators. In addition, weights will change with exchange rate movements. Appreciating currencies will experience increasing weights and depreciating currencies decreasing weights. This may require a correction mechanism for political acceptability. In Europe, weights were rescaled by political authorities every five years. From an economic viewpoint, weights depend critically on the purpose of the basket currency: is it a reference indicator, is it a currency for international transactions, or is it a parallel currency? Thus, before weights are to be discussed a clear vision of the role of the basket currency would be desirable. The vastly different growth performance among Asian economies also suggests a preference to forward rather than backward-looking measures. Turning then to the different functions of a basket currency, we examine the use of basket currencies as a divergence indicator, or as a financial instrument in regional finan